diff --git a/hw/pckbd.c b/hw/pckbd.c
index 7998aa6..554fbe4 100644
--- a/hw/pckbd.c
+++ b/hw/pckbd.c
@@ -50,7 +50,9 @@
  #define KBD_CCMD_WRITE_MOUSE    0xD4    /* Write the following byte to 
the mouse */
  #define KBD_CCMD_DISABLE_A20    0xDD    /* HP vectra only ? */
  #define KBD_CCMD_ENABLE_A20     0xDF    /* HP vectra only ? */
-#define KBD_CCMD_RESET            0xFE
+#define KBD_CCMD_PULSE_BITS_3_0 0xF0    /* Pulse bits 3-0 of the output 
port P2. */
+#define KBD_CCMD_RESET          0xFE    /* Pulse bit 0 of the output 
port P2 = CPU reset. */
+#define KBD_CCMD_NO_OP          0xFF    /* Pulse no bits of the output